diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 19a600443b9e..f8db3fe616df 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -5376,16 +5376,17 @@ __xfs_bunmapi(
 		}
 		div_u64_rem(del.br_startblock, mp->m_sb.sb_rextsize, &mod);
 		if (mod) {
+			xfs_extlen_t off = mp->m_sb.sb_rextsize - mod;
+
 			/*
 			 * Realtime extent is lined up at the end but not
 			 * at the front.  We'll get rid of full extents if
 			 * we can.
 			 */
-			mod = mp->m_sb.sb_rextsize - mod;
-			if (del.br_blockcount > mod) {
-				del.br_blockcount -= mod;
-				del.br_startoff += mod;
-				del.br_startblock += mod;
+			if (del.br_blockcount > off) {
+				del.br_blockcount -= off;
+				del.br_startoff += off;
+				del.br_startblock += off;
 			} else if (del.br_startoff == start &&
 				   (del.br_state == XFS_EXT_UNWRITTEN ||
 				    tp->t_blk_res == 0)) {
@@ -5403,6 +5404,7 @@ __xfs_bunmapi(
 				continue;
 			} else if (del.br_state == XFS_EXT_UNWRITTEN) {
 				struct xfs_bmbt_irec	prev;
+				xfs_fileoff_t		unwrite_start;
 
 				/*
 				 * This one is already unwritten.
@@ -5416,12 +5418,13 @@ __xfs_bunmapi(
 				ASSERT(!isnullstartblock(prev.br_startblock));
 				ASSERT(del.br_startblock ==
 				       prev.br_startblock + prev.br_blockcount);
-				if (prev.br_startoff < start) {
-					mod = start - prev.br_startoff;
-					prev.br_blockcount -= mod;
-					prev.br_startblock += mod;
-					prev.br_startoff = start;
-				}
+				unwrite_start = max3(start,
+						     del.br_startoff - mod,
+						     prev.br_startoff);
+				mod = unwrite_start - prev.br_startoff;
+				prev.br_startoff = unwrite_start;
+				prev.br_startblock += mod;
+				prev.br_blockcount -= mod;
 				prev.br_state = XFS_EXT_UNWRITTEN;
 				error = xfs_bmap_add_extent_unwritten_real(tp,
 						ip, whichfork, &icur, &cur,